An innovative lab-scale strategy for the evaluation of Grape Processing Residues (GPR) filterability: Application to GPR valorization by ultrafiltration

The objective of this work was to characterize the foulant propensity of three Grape Processing Residues (GPR) in relation with their physicochemical properties. Therefore, a physicochemical characterization of GPR was firstly carried-out, with a focus on the separation/characterization of relevant size-classes of particles. Then, lab-scale experiments were performed using a dead-end filtration module with different membranes (three average pore diameters) in order to identify for each GPR the main foulant size-classes of particles and the related fouling mechanisms. Results showed that this study allowed getting more insight into how different fractions of GPR are involved in membrane fouling according to their size. Moreover, size-cartographies of GPR foulant compounds were built to provide a better understanding and control of membrane fouling. The obtained results showed that it was possible to use this simple and cost-effective tool to choose the appropriate filtration conditions. Industrial relevance The valorization of Grape Processing Residues (GPR) is a major economic and ecological challenge. GPR contain a high amount of phenolic compounds, well known for their several biological properties. In the light of this, membrane technologies have been widely used for the extraction and the purification of these bioactive compounds from GPR. However, the performance of these processes is highly challenged by membrane fouling, which is partially dependent on the feed suspension characteristics. To date, different operating strategies have been used industrially to prevent membrane fouling. However, the use of costly and time-consuming strategies has not often been validated by characterization of the feed suspension prior to filtration. Thus, it is mandatory to analyze GPR intrinsic characteristics in relation with their fouling in order to identify the appropriate operation conditions for large-scale filtration. For this purpose, an innovative strategy was developed in this work. This study was useful to develop a simple and cost-effective tool providing reliable guidelines for the development of efficient pilot-scale processes for the extraction of phenolic compounds from GPR.